Flight Results of ESTCube-1 Attitude Determination System

Abstract

This paper presents the characterization and in-orbit validation of the ESTCube-1 attitude determination system (ADS). ESTCube-1 is a one-unit CubeSat built by students and launched on May 7, 2013, to a Sun-synchronous, 700-km, polar low Earth orbit. Its primary mission is to centrifugally deploy a tether as a part of the first in-orbit demonstration of electric solar wind sail (i.e., E-sail) technology. The ADS uses magnetometers, gyroscopic sensors, Sun sensors, and an unscented Kalman filter for attitude determination. Here the performance of commercial off-the-shelf (COTS) sensors and results from tuning the system is shared; recalibration, software, and Kalman filter adjustments. The system is validated by comparing the attitude determined by the on-board ADS with the attitude determined from on-board camera images. Uncertainty budgets for both attitude determination methods are estimated. The expanded uncertainty of comparison (95% confidence level, k=2) is 1.75° and the maximum difference between attitudes determined by both methods is 1.43°.